Asymmetric ansa-zirconocenes containing a 2-methyl-4-aryltetrahydroindacene fragment: Synthesis, structure, and catalytic activity in propylene polymerization and copolymerization

Article abstract of DOI:10.1021/om200610b

A set of asymmetric bis-indenyl zirconium SiMe₂-bridged ansa-complexes, containing 2-isopropyl-4-arylindenyl and 2-methyl-4- aryltetrahydroindacenyl fragments, have been synthesized. These complexes demonstrate better catalytic activity, stereoselectivty, and polymer molecular weight capability in propylene homo-and copolymerization in comparison to analogues without a tetrahydroindacenyl fragment.

Full text of DOI:10.1021/om200610b

ARTICLE
pubs.acs.org/Organometallics
Asymmetric ansa-Zirconocenes Containing a 2-Methyl-4-
aryltetrahydroindacene Fragment: Synthesis, Structure, and Catalytic
Activity in Propylene Polymerization and Copolymerization
Ilya E. Nifant’ev,* Pavel V. Ivchenko, and Vladimir V. Bagrov
Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, Russia 119991
Yoshikuni Okumura*
Corporate Research and Development Center, Showa Denko K. K., 2 Nakanosu, Oita 870-0189, Japan
Michael Elder*
Grace Davison Specialty Catalysts, Columbia, Maryland, United States
Andrei V. Churakov
N.S. Kurnakov Institute of General and Inorganic Chemistry RAS, 31 Leninsky Prospect, Moscow, Russia 119991
S Supporting Information
b
ABSTRACT: A set of asymmetric bis-indenyl zirconium SiMe2-
bridged ansa-complexes, containing 2-isopropyl-4-arylindenyl and
2-methyl-4-aryltetrahydroindacenyl fragments, have been synthe-
sized. These complexes demonstrate better catalytic activity, stereo-
selectivty, and polymer molecular weight capability in propylene
homo- and copolymerization in comparison to analogues without a
tetrahydroindacenyl fragment.
’ INTRODUCTION
appears to be much less active in propylene polymerization. On
the other hand, dimethylsilylenebis(2-methyl-4-phenylindenyl)di-
chlorozirconium (1) (Scheme 1), an effective propylene polymer-
ization catalyst,3 is less productive for ethylene.4 So, we can regard
type 1 ansa-complexes as prototypes for the creation of effective
stereoregular ethyleneꢀpropylene copolymerization catalysts.
The use of type 1 zirconocenes for the preparation of high
molecular weight, low ethylene content copolymers has been
described.5 However, preparation of higher ethylene content
copolymers has been limited due to transfer to ethylene termina-
tion reaction associated with this type of ansa-metallocene
structure.2a,5 One of us6 showed that the replacement of one
methyl group in position 2 of the indenyl ring by an isopropyl
substituent in bis(2-methyl-4-arylindenyl) complexes (structure
2, Scheme 1) would lead to a noticeable change of these
complexes’ catalytic properties, compared to type 1 symmetric
complexes. In particular, homopolymers with increased regio-
selectivity and polymer melting points were observed, and
adding ethylene to the catalytic system based on complex 2 does
not result in a significant decrease of the polymer molecular
Today, after more than 25 years of studies on finding effective
single-site catalysts for propylene isotactic polymerization, re-
searchers are more and more often addressing the processes of
obtaining saturated hydrocarbon copolymers of different com-
position and origin.
These compounds, which combine elasticity, impact resis-
tance, and strength, could potentially be used for substitution of
polyvinyl chloride and polydiene polymers and copolymers.
Ethyleneꢀpropylene copolymers containing relatively long
(more than 10 subunits) isotactic polypropylene fragments
with ethylene insets as well as heterophasic copolymers with
rubber fractions of more uniform composition seem to be of
particular industrial interest.1 Obviously, only group 4 ansa-
metallocenes or similar sterically rigid single-site metal com-
plexes that can catalyze isotactic polypropylene formation (i.e.,
that have C1 or C2 symmetry) would catalyze the formation of
copolymers of this type.2
Unlike ZieglerꢀNatta classical heterogeneous catalysts, the
comparative activity of different structural type zirconocenes in
reactions with ethylene and propylene is widely variable. Zirco-
nocene dichloride, the simplest specimen of the class, catalyzes
ethylene polymerization in the presence of MAO, though it
Received: July 9, 2011
Published: October 12, 2011
r
2011 American Chemical Society
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weight,6b,7 although the catalytic activity of 2 decreases slightly.
Also, type 2 metallocenes could be supported on silica without
significant deactivation.
catalytic activity in propylene polymerization and ethyleneꢀ
propylene copolymerization.
Preparation of Indenes. The commonly used effective
method of 2-methyl-4-arylindene synthesis starts from 2-methyl-
4-haloindanone and includes a Suzuki coupling reaction and
reduction of 2-methyl-4-arylindanone to the corresponding
indanol with subsequent dehydration.12 The key intermediate in
the preparation of the target tetrahydroindacenes is 2-methyl-
3,5,6,7-tetrahydro-s-indacen-1(2H)-one (4).
Zirconocenes' catalytic activity can also be stimulated by the
addition of electron-donor substituents to the indenyl fragments
of the corresponding ligands, which would increase stability of
alkylzirconocene cationic intermediates and the concentration of
catalytic centers. Applying these substitutions to ansa-complexes'
lateral positions adjacent to the pendent phenyl group can also
provide subtle changes to ligand sterics at the monomer co-
ordination site. Methyl substituents at these positions have been
described for type 2, type 1, and similar heterocyclic-containing
ansa-complexes with increases in catalyst stereoselectivity and
polymer molecular weight capability being reported.6b,8,9 Recent
theoretical and experimental research10,11 suggest that deriva-
tives of 1,5,6,7-tetrahydro-s-indacene might be used as perspec-
tive indenyl-type electron-donor ligands, which resulted in target
structural type 3 (Scheme 1).
There are quite a few common methods for substituted
indanone synthesis, the most simple of which is arene acylation
by halogencarbonic or unsaturated carbonic acids derivatives
followed by Nazarov cyclization of the intermediate aryl vinyl
ketones. This reaction proceeds nonselectively for alkyl- and 1,2-
dyalkylbenzols.6 Indane, to the contrary, usually produces a
specific isomer, compound 4.13 2-Bromo-2-methylpropionyl
bromide (catalyst 2.2ꢀ2.5 equiv of AlCl3, CH2Cl2) was used
as the acylation agent. Methacryloyl chloride can also be used in
this reaction, but the accompanying polymeric byproduct ad-
versely affects the synthesis and purification of the product. The
bromating reaction with compound 4 was shown to be possible
in the same reaction mixture with no significant decrease in yield
of the resulting 4-bromohexahydroindacenone 5 yield, so there is
no need for the isolation and purification of 4 and its analogues.
Suzuki coupling reactions with 5 gave 4-arylhexahydroindace-
nones 6ꢀ8, and their further reduction and dehydration resulted
in aryltetrahydroindacenes 9ꢀ11 (Scheme 2).
’ RESULTS AND DISCUSSION
In an effort to address the role of the electron-donor indenyl-
type unit, we prepared a number of substituted tetrahydroinda-
cenes and type 3 zirconocenes therefrom and tested their
Scheme 1
Reacting compound 4 with two equivalents of Br2 produced
dibromoderivative 12, the arylation of which by the Suzuki
method with subsequent reduction/dehydration resulted in
diaryltetrahydroindacene 14 (Scheme 3).
Preparation of Bis-indenyl Ligands and Zirconocenes.
The most common method of obtaining asymmetric bis-indenyl
compounds with a dimethylsilylene bridge is the interaction of
lithium and chlorodimethylsilyl derivatives of the corresponding
indenes. The bis-indenyl compound (complex 2 “ligand”) was
obtained previously in high yield by the usage of CuCN as
catalyst and ether solvent.6 The same method was used for the
synthesis of bis-indenyl compounds 15ꢀ18 (Scheme 4).
Zirconocene 2 was synthesized by reacting the dilithium
derivative of bis-indenyl ligand with ZrCl4 in an etherꢀtoluene
solvent system. The pseudo-rac-form was isolated by fractional
crystallization.6
Scheme 2
The reaction of dilithium derivatives of 15 and 16 and ZrCl4 in
ether and etheral solvents, toluene, or CH2Cl2 did not result in a
high yield of the target zirconocenes. The reactions were
accompanied by a large amount of polymeric byproduct, which
adversely affected the yield of ansa-zirconocenes and separation
of diastereometric forms. The reaction of dilithium derivatives 15
and 16 and ZrCl4 in an inert solvent (pentane) with minimum
quantities of ether proved to be a significantly more effective
synthesis method. Following these conditions ansa-complexes
19 and 20 were finally obtained as a mixture of pseudo-rac- and
Scheme 3
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Organometallics
ARTICLE
pseudo-meso-forms in ∼1:1 ratio. This stage of the experiment
appeared to be the most difficult due to the fact that type 3
compounds proved to be more soluble than compound 2 despite
the approximately similar solubility of their diastereomeric
forms: using crystallization methods for diastereomer separation
was unsuccessful.
At the same time, 21 and 22 were obtained as a mixture of
diastereomers with moderate yield (∼70%) by the reaction of
17/18 dilithium derivatives with ZrCl4 in a ∼1:1 etherꢀpentane
mixture. Pure pseudo-racemic 21 and 22 were separated by
crystallization from toluene with moderate to low (22% and
3.5%) yields.
not increase. We can therefore conclude that in the case of
nonsymmetric 19 and 20 complexes there is no rearrangement of
the pseudo-meso-forms into the pseudo-rac-forms. However the
foremost ones break up and allowed us to isolate the diaster-
eometrically pure pseudo-rac-19/20, although with a moderate
yield. In contrast, continuous heating of the 21 and 22 rac-/
meso-mixture in dimethoxyethane leads to simultaneous decom-
position of diastereomers with final complete dissipation of zirco-
nocene signals in the 1H NMR test. Structural formulas of pseudo-
rac forms of the obtained complexes are given in Scheme 5.
X-ray Structure Determination of 20. The molecular struc-
ture of racemic complex 20 is shown in Figure 1. Selected bond
lengths and angles are listed in Table 1. The coordination environ-
ment of the Zr atom may be treated as a distorted tetrahedron
(assuming that η5-C5 rings occupy one coordination site). The
ZrꢀC distances vary over a wide range, 2.457(5)ꢀ2.636(5) Å. The
latter is typical for indenyl zirconium complexes15,16 and reflects the
tendency of Zr atoms to form a η3,η2 linkage with indenyl ligands.
As expected, the ZrꢀC(3) and ZrꢀC(33) bonds are the shortest
since these carbon atoms are linked by a small-scale ꢀSiMe2ꢀ
spacer. Both indenyl ligands are planar within 0.057(4) Å and form a
dihedral angle of 64.2(1)°. The Cambridge Structural Database
(ver. 5.31, May 2010) contains data for 24 nearly related ansa-
bis(indenyl)zirconocene dichlorides with a ꢀSiMe2ꢀ bridge.17 The
main geometric parameters of molecule 20 are very close to the
respective average values retrieved from CSD (see Table 1).
Polymerization Results. Complex 23 synthesized before6
was used for comparison.
A method for generating pure rac-forms of ansa-zirconocenes
by continuous heating of rac-/meso-mixtures in dimethoxyethane
(or in other etheral solvents) in the presence of lithium or
magnesium chlorides was suggested in ref 14. The authors
demonstrated that a quantitative conversion of the meso-form
into the rac-form could be obtained under these circumstances
for some bis-indenyl complexes. We tried this approach with rac/
meso-mixtures of 19 and 20 monitoring the course of the reaction
1
by taking reaction mixture samples and scanning them by H
NMR spectroscopy. The results showed prolonged heating of
the diastereometric mixtures in DME together with LiCl led to a
gradual disappearance of the pseudo-meso-form complexes' sig-
nals and simultaneous appearance of nonidentified broadened
signals although the relative intensity of the pseudo-rac-forms did
Scheme 4
The results of a series of propylene polymerizations using
supported complexes (silica, activation by MAO) in liquid
propylene at 65 °C are summarized in Table 2. Propylene
polymerizations were done both in the absence and in the
presence of hydrogen (0.5 L per 1 L of liquid monomer). As
can be seen from the table, there is a wide range of catalytic
activity observed and hydrogen has a significant activating effect
on all the catalysts.
The obtained data clearly show that substitution of the specific
indenyl fragment with the methyl group in the 2 position by
tetrahydroindacenyl can sometimes lead to significant increases
in catalytic activity and polypropylene molecular mass. The
ligand effects on polymer Tm are more subtle; however the
general trend is higher isoselectivity with complexes incorporat-
ing the tetrahydroinacenyl moiety.
Scheme 5
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Figure 1. Molecular structure of 20. Displacement ellipsoids are shown at the 50% probability level. Hydrogen atoms are omitted for clarity.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 20 and Respective Geometric Parameters from CSD Data for ansa-[(η5-
Inden-1-yl)2SiMe2]ZrCl2 Derivatives
20
CSD data, range (average)
2.393ꢀ2.454 (2.423)
Zr(1)ꢀCl(1)
2.4159(16)
2.238
Zr(1)ꢀCl(2)
Zr(1)ꢀCp(2)*
Zr(1)ꢀC(33)
Zr(1)ꢀC(32)
Zr(1)ꢀC(34)
Zr(1)ꢀC(31)
Zr(1)ꢀC(42)
Si(1)ꢀC(33)
C(31)ꢀC(32)
C(32)ꢀC(33)
C(33)ꢀC(34)
C(34)ꢀC(42)
C(42)ꢀC(31)
2.4113(16)
2.234
ZrꢀCl
Zr(1)ꢀCp(1)a
Zr(1)ꢀC(3)
ZrꢀCp
ZrꢀCCp
2.225ꢀ2.272 (2.241)
2.404ꢀ2.517 (2.467)
2.441ꢀ2.575 (2.493)
2.477ꢀ2.592 (2.549)
2.545ꢀ2.631 (2.584)
2.604ꢀ2.681 (2.644)
1.855ꢀ1.905 (1.876)
1.367ꢀ1.442 (1.406)
1.339ꢀ1.535 (1.434)
1.400ꢀ1.516 (1.447)
1.288ꢀ1.660 (1.439)
1.387ꢀ1.446 (1.412)
94.2ꢀ100.1 (97.1)
2.457(5)
2.523(5)
2.521(5)
2.608(5)
2.626(5)
1.858(5)
1.405(7)
1.437(7)
1.469(7)
1.428(7)
1.422(7)
96.86(5)
127.9
2.471(5)
2.499(5)
2.531(5)
2.578(5)
2.636(5)
1.875(6)
1.413(7)
1.424(7)
1.457(7)
1.437(7)
1.419(7)
Zr(1)ꢀC(2)
Zr(1)ꢀC(4)
Zr(1)ꢀC(1)
Zr(1)ꢀC(9)
Si(1)ꢀC(3)
SiꢀCCp
CCpꢀCCp
C(1)ꢀC(2)
C(2)ꢀC(3)
C(3)ꢀC(4)
C(4)ꢀC(9)
C(9)ꢀC(1)
Cl(1)ꢀZr(1)ꢀCl(2)
Cp(1)ꢀZr(1)ꢀCp(2)
C(3)ꢀSi(1)ꢀC(33)
C(23)ꢀSi(1)ꢀC(24)
C(2)ꢀC(3)ꢀSi(1)
C(4)ꢀC(3)ꢀSi(1)
Cp(1)ꢀC(3)ꢀSi(1)
ClꢀZrꢀCl
CpꢀZrꢀCp
CCpꢀSiꢀCCp
MeꢀSiꢀMe
CCpꢀCCpꢀSi
CCpꢀCCpꢀSi
CpꢀCCpꢀSi
126.3ꢀ129.5 (128.2)
94.1ꢀ95.7 (94.9)
94.4(2)
103.7(3)
127.2(4)
124.6(4)
164.5
100.0ꢀ112.1 (108.0)
118.9ꢀ129.1 (124.7)
121.9ꢀ132.5 (126.7)
158.6ꢀ167.7 (163.1)
C(32)ꢀC(33)ꢀSi(1)
C(34)ꢀC(33)ꢀSi(1)
Cp(2)ꢀC(33)ꢀSi(1)
127.2(4)
124.1(4)
162.8
a Cp(1) and Cp(2) denote the centers of η5-C5 rings (C(1), C(2), C(3), C(4), C(9) and C(31), C(32), C(33), C(34), C(42), respectively).
Propyleneꢀethylene copolymerizations were conducted with
the same number of complexes. The results of experiments are
given in Table 3. Ethylene also has a strong activating effect on
the catalysts, and substitution of the indenyl fragment by tetra-
hydroindacenyl can lead to significant increases in catalytic
activity and copolymer molecular mass. The copolymer molec-
ular mass capacity of 20 and 21 is sufficient to make polymer-
ization under ethylene + hydrogen conditions feasible.
The obtained data for both homo- and copolmyerizations are
presented in Figure 2.
Complex 20 was also tested in propylene homopolymeriza-
tions under homogeneous catalyst condtions. Results are given in
Table 4.
The relatively high Tm of polypropylene with this class of C1-
symmetric complexes on a supported catalyst was confirmed by 13C
NMR analysis, and microstructures of polypropylene were found to
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Table 2. Catalytic Properties of Supported (silica/MAO, Al/Zr m.r. = 210, 0.016 mmol Zr/g cat) Complexes in Propylene
Polymerizationa (MAO, 65 °C, liquid propylene, 1 h)
c
no.
H2
act. (kg/g cat h)
act. (kg/mmol Zr h)
melting point (°C)
I.V. b (dL/g)
Mw , ꢁ 103c
Mw/Mn
19
19
20
20
21
21
22
22
23
23
ꢀ
+
1.0
3.4
1.0
3.9
2.0
3.9
1.9
3.9
0.6
2.7
63
213
63
157.8
155.7
159.0
157.6
157.4
159.3
160.3
159.1
152.5
154.3
4.11
2.22
3.72
1.86
4.57
1.74
2.77
2.06
2.53
1.94
591
298
548
251
795
219
355
253
356
240
3.4
3.5
2.7
2.7
2.8
2.2
2.1
1.9
2.3
2.2
ꢀ
+
244
125
244
119
244
38
ꢀ
+
ꢀ
+
ꢀ
+
169
a Triethylaluminum was used as poison scavenger. b Intrinsic viscosity number, determined in decalin at 135 °C; for details see Experimental Section.
c Mw and PDI data obtained by GPC.
Table 3. Catalytic Properties of Supported (silica/MAO, Al/Zr m.r. = 210, 0.016 mmol Zr/g cat) Complexes in Propyleneꢀ
Ethylene Copolymerizationa (MAO, 65 °C, 3.5 L of liquid propylene, 200 g of ethylene, 32 atm, 1 h)
I.V.b (dL/g)
Mw , ꢁ 103c
Mw/Mn
melting point (°C)
C2, %d
c
no.
act. (kg/g cat h)
act. (kg/mmol Zr h)
19
20
21
22
23
3.1
7.4
4.2
4.2
3.4
194
463
263
263
213
4.91
4.80
4.95
4.30
2.86
728
909
994
594
433
3.9
3.1
3.7
2.3
2.3
123.5
123.3
119.7
108.1
125.8
4.7
3.8
4.7
6.2
3.2
a Triethylaluminum was used as poison scavenger. b Intrinsic viscosity number, determined in decalin at 135 °C; for details see Experimental Section.
c Mw and PDI data obtained by GPC. d C2 content obtained by FTIR; for details see Experimental Section.
have higher stereo- and regioregularity than those with C2-symmetric
complexes such as dimethylsilylenebis(2-methyl-4-phenylindenyl)
dichlorozirconium (more than 0.80% regiodefects).
range of polymer molecular weights and crystallinity. Metallo-
cene catalysts’ high hydrogen response for molecular weight
control and the ability to produce copolymers of more uniform
composition than multisite catalysts is of particular interest for
this type application. Introduction of the 5,6-substituions into
the specific position on the indene moiety with a pendent aryl
group results in further increases in activity, molecular weight
capability (both homo and EP copolymer), and isoselectivity. Of
the compounds synthesized, complex 20 appears to be a distinct
leader and provides some new opportunities for two-stage
impact copolymerization where both a stiff homopolymer matrix
and high molecular weight EP rubber fraction are needed. A
relatively simple Si/MAO preparation was used to screen
catalysts in this study; however the characteristics of the sup-
port/activator can influence metallocene performance, and more
research is needed in this area.
These results could be explained by C1-symmetric structural
features and two different coordination sites: one is the site with
2-methyl (or generally a primary alkyl) and is sterically more
open; the other site has 2-isopropyl (or generally an alpha-
branched alkyl such as a secondary alkyl) and is sterically more
hindered. Each site has different features in propylene polymer-
izations, and both stereo- and regioselectivity of propylene
polymerization at insertion into the more sterically hindered site
(“2-isopropyl site”), in which the polymer chain sits in the open
site (“2-methyl site”), are expected to be higher than those at the
insertion into the 2-methyl site. Back skip of the polymer chain18
from the 2-isopropyl site to the 2-methyl site increases the chance
of propylene insertion into the 2-isopropyl site (Figure 4).
In the copolymerization of propylene with ethylene we suppose
that the 2-isopropyl group makes it relatively difficult to transfer to
ethylene following a propylene 2,1-insertion and reduces the
chance of termination reaction with ethylene and increases the
molecular weight of ethyleneꢀpropylene copolymer.19 Recent
computational studies on ethylene and alpha-olefin copolymeri-
zation with metallocenes lend support to the idea that termination
by transfer to ethylene following a propylene 2,1-regioerror can be
a primary pathway for reducing polymer molecular weight.20
’ EXPERIMENTAL SECTION
General Considerations. All operations were performed under
argon by using standard Schlenk technique or under vacuum using
sealed glass “equipped-with-everything” systems. Indane, 2-bromo-2-
methylpropionyl bromide, AlCl3, and BuLi (1.6 or 2.5 M solution in
hexanes) (Aldrich) and MAO solution in toluene (Albemarle) were
used as purchased. Sylopol 948 (Grace-Davison) was calcined at 600 °C
before use. SiMe2Cl2 (Aldrich) was refluxed over Al and distilled before
use. Toluene, ether, THF, and dimethoxyethane (DME) were dried over
Na/benzophenone. CH2Cl2 was refluxed and distilled over CaH2.
Pentane was distilled over Na/K alloy. 2-Isopropyl-7-phenyl-1H-indene,
the corresponding bridged ligand, and zirconocene 23 were prepared in
’ CONCLUSIONS
The C1-symmetric single-site catalysts presented in this study
provide access to propylene-rich EP copolymers over a broad
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Figure 2. Polymerization test results for 19ꢀ22 and bis-indenyl complex 23.
Table 4. Catalytic Properties of Non-Supported 20 in Propylene Polymerizationa (0.02 g of metallocene, MAO, Al/Zr m.r. = 28700,
65 °C, 300 g of liquid propylene, 25 min)
c
H2
act. (kg/mmol Zr hour)
melting point (°C)
I.V.b (dL/g)
Mw , ꢁ 103c
Mn , ꢁ 103c
Mz , ꢁ 103c
Mw/Mn
ꢀ
570
165.6
167.9
4.70
2.12
1060
305
357
140
2353
585
3.0
2.2
+
2800
a Triisobutylaluminum (4.0 mmol) was used as poison scavenger; for details see Experimental Section. b Intrinsic viscosity number, determined in
decalin at 135 °C; for details see Experimental Section. c Mw and PDI data obtained by GPC.
accordance with published procedures.5 NMR spectra were recorded on
a Varian XR-400 spectrometer (400 MHz). Mass spectra were measured
using a Hewlett-Packard series 6890 instrument that was equipped with
a series 5973 mass analyzer (El, 70 eV).
4-Bromo-2-methyl-3,5,6,7-tetrahydro-s-indacen-1(2H)-one (5). 4
(31 g, 162 mmol) was added to a suspension of anhydrous AlCl3 (50 g,
370 mmol) in 200 mL of chloroform while stirring vigorously at 0 °C.
After stirring for one hour, a solution of bromine (8 mL, 160 mmol) in
20 mL of chloroform was added dropwise at 0 °C, and the mixture was
then stirred overnight. The reaction mixture was poured into 500 g of
an ice/water mixture. The organic phase was separated off, washed
with 5% aqueous NaHCO3 and water, and then dried over magnesium
sulfate. Filtration and removal of the solvent under reduced pressure
gave 50 g of a red oil. The mixture was separated by column chro-
matography on silica gel using methylene chloride as eluent. This gave
18.7 g (44% yield) of compound 5 (yellow oil). Found, %: C, 58.96; H,
4.99; O, 6.01. Calcd for C13H13BrO, %: C, 58.89; H, 4.94; O, 6.03. 1H
NMR (CDCl3, 20 °C): δ 1.32 (d, 1H), 2.15 (t, 2H), 2.59 (dd, 1H), 2.74
(m, 1H), 2.98 (m, 4H), 3.28 (dd, 1H), 7.48 (s, 1H). 13C NMR (CDCl3,
20 °C): δ 16.2, 25.6, 33.2, 34.3, 35.5 42.3, 117.8, 118.7, 137.1, 145.8,
151.8, 152.4, 208.2.
2-Methyl-3,5,6,7-tetrahydro-s-indacen-1(2H)-one (4). Anhydrous
AlCl3 (50.7 g, 377 mmol) was slowly added at 0 °C to a mixture of
indane (19.3 g, 163 mmol) and 2-bromo-2-methylpropionyl bromide
(38.3 g, 167 mmol) in 500 mL of methylene chloride over a period of
30 min. The reaction mixture became dark red. The suspension was stirred
at room temperature for 17 h and then poured into 200 g of crushed ice
and 100 mL of concentrated HCl. The organic phase was separated, the
water phase was extracted by CH2Cl2 (3 ꢁ 50 mL), and the combined
organic phase was washed subsequently with 100 mL of saturated
sodium hydrogen carbonate solution and with 200 mL of water, dried
over anhydrous sodium sulfate, and filtered. Removal of the solvent
under reduced pressure gave 31 g of compound 4 as a reddish-brown oil.
According to GC-MS, the content of 4 in the oil was >90%.
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Figure 3. 13C NMR spectrum (methyl region) of polypropylene in Table 2. Upper: Run 20/+ in Table 2 (mrrm = 0.21%; 2,1 = 0.29%; 1,3 = 0.06%).
Lower: Run 22/ꢀ in Table 2 (mrrm: undetectable; 2,1 = 0.20%; 1,3 = 0.20%).
4-(4-tert-Butylphenyl)-2-methyl-3,5,6,7-tetrahydro-s-indacen-
1(2H)-one (7). Pd(OAc)2 (0.3 g, 3 mol %) and triphenylphosphine
(0.7 g, 6 mol %) were added toa well-stirredmixture of5 (12 g, 45 mmol),
4-tert-butylphenylboronic acid (11.2 g, 63 mmol), and Na2CO3 (13.4 g,
126 mmol) in 170 mL of DME/56 mL of water. The reaction mixture was
refluxed for 6 h, poured into water, and extracted with methylene chloride
(5 ꢁ 100 mL). The combined organic phases were washed with water and
dried over MgSO4. After removal of the solvent, the crude product was
chromatographed on silicagel(hexane/CHCl3 from4:1to 1:1). Thisgave
10 g (70% yield) of compound 7 as a viscous oil. Found, %: C, 86.83; H,
8.35; O, 4.64. Calcd for C23H26O, %: C, 86.75; H, 8.23; O, 5.02. 1H NMR
(CDCl3, 20 °C): δ 1.26 (d, J = 7.2 Hz, 3H), 1.38 (s, 9H), 2.07 (m, 2H),
2.56 (m, 1H), 2.69 (m, 1H), 2.84 (dd, 2H), 2.99 (dd, 2H), 3.21 (m, 1H),
7.40 (d, J = 8.2 Hz, 2H), 7.46 (d, J=8.3 Hz, 2H), 7.59 (s, 1H).
4-(2,5-Dimethylphenyl)-2-methyl-3,5,6,7-tetrahydro-s-indcen-
1(2H)-one (8). Obtained by the method used for 7. Found, %: C, 86.80;
H, 7.68; O, 5.52. Calcd for C21H22O, %: C, 86.85; H, 7.64; O, 5.51. Yield:
77% (yellow oil). EIMS: m/z (%) 290 (M+, 100), 269 (92), 247 (43),
226 (31), 203 (22), 165 (8).
6-Methyl-4-phenyl-1,2,3,5-tetrahydro-s-indacene (9). A mixture of
6 (6.4 g, 24.4 mmol) and NaBH4 (2.10 g, 55 mmol) in 40 mL of toluene
was heated to 50 °C, 7 mL of methanol was added slowly, and the
reaction mixture was stirred at 50 °C for 3 h. After cooling to room
temperature 12 mL of water and 40 mL of 1 M HCl were added, and the
mixturewas stirredfor30 min. After phase separation thewater phase was
extracted with toluene. The organic phase was evaporated, and the
residue was taken up in 100 mL of toluene and mixed with 100 mg of p-
toluenesulfonic acid. Water was distilled off from this reaction mixture by
refluxing for 1 h with a water separator until the reaction was complete.
The reaction mixture was washed once with 100 mL of NaHCO3
aqueous solution and dried over MgSO4. After removal of the solvent,
the residue was dried in vacuo and purified by column chromatography
(200 g of silica gel, heptane/Et2O, 9:l). Yield: 5.1 g (85%). Found, %: C,
92.56; H, 7.44. Calcd for C19H18, %: C, 92.64; H, 7.36. 1H NMR (CDCl3,
20 °C): δ 2.04 (t, 2H), 2.08 (s, 3H), 2.77 (t, 2H), 2.97 (t, 2H), 3.15 (s,
2H), 6.47 (s, 1H), 7.13 (s, 1H), 7.35ꢀ7.48 (m, 5H).
Figure 4. Supposed propylene polymerization mechanism.
4-Phenyl-2-methyl-3,5,6,7-tetrahydro-s-indacen-1(2H)-one (6). 5
(10 g, 37.7 mmol), phenylboronic acid (5.5 g, 45.3 mmol), Na2CO3
(8.8 g,, 80 mmol), 80 mL of ethylene glycol, and 12 mL of water were
placed under a protective argon atmosphere and heated to 80 °C. While
stirring vigorously freshly prepared catalyst solution of 20 mg of
Pd(OAc)2, 260 mg of 3,30,300-phoshinidynetris(benzenesulfonic acid)-
trisodium salt (TPPTS) in 4 mL of water was added, and the reaction
mixture was refluxed for 3 h. After cooling to room temperature, 40 mL
of water was added, and the ethylene glycol phase was extracted with
toluene (3 ꢁ 80 mL). The combined organic phases were washed by 2 ꢁ
100 mL of aqueous NaCl and dried over Na2SO4. Removal of solvents
gave 9.6 g of brown oil, which was gradually crystallized (97%, GC-MS).
Found, %: C, 87.0; H, 7.00; O, 6.00. Calcd for C19H18O, %: C, 86.99; H,
6.92; O, 6.10. 1H NMR (CDCl3, 20 °C): δ 1.26 (d, 3H), 2.08 (m, 2H),
2.52 (dd, 1H), 2.68 (m, 1H), 2.81 (m, 2H), 3.00 (t, 2H), 3.17 (dd, 1H),
7.31 (d, 2H), 7.39(dd, 1H), 7.45 (d, 2H), 7.61 (s, 1H).
4-(4-tert-Butylphenyl)-6-methyl-1,2,3,5-tetrahydro-s-indacene (10).
A solution of 7 (9.9 g, 31 mmol) in Et2O (30 mL) was added dropwise at
0 °C to a solution of LiAlH4 (0.6 g, 16 mmol) in Et2O (I00 mL). The
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reaction mixture was allowed to warm to room temperature and stirred
for 1 h. A 50 mL amount of 5% hydrochloric acid was added. Benzene
(200 mL) was added, and the organic phase was separated, washed by
water, dried over MgSO4, filtered, and concentrated to a residual volume
of ∼150 mL. p-Toluenesulfonic acid (0.5 g) was added, and the mixture
was refluxed for 1 h with a water separator until the reaction was com-
plete. The solution was cooled to room temperature, washed with 5%
aqueous NaHCO3, and dried over MgSO4. Evaporation of the solvent
gave pure 10 in quantitative yield. Found, %: C, 91.30; H, 8.70. Calcd for
C23H26, %: C, 91.34; H, 8.66. 1H NMR (CDCl3, 20 °C): δ 1.36 (s, 9H),
2.02 (m, 2H), 2.06 (s, 3H), 2.78, 2.84 (dd, 2H), 2.95 (dd, 2H), 3.17, 3.29
(s, 2H), 6.43ꢀ6.45 (m, 1H), 7.10 (s, 1H), 7.30 (d, J = 8.2 Hz, 2H), 7.41
(d, J = 8.2 Hz, 2H).
4-(2,5-Dimethylphenyl)-6-methyl-1,2,3,5-tetrahydro-s-indacene (11).
Ketone 8 (24.0 g, 80.6 mmol) was dissolved in 300 mL of methyl-tert-butyl
ether and treated with 46 mL of an ethereal solution of LiAIH4 (1 M,
46 mmol) at 0 °C. After stirring at room temperature for 2 h, 20 mL of a
2 M HCl solution was added cautiously. The organic phase was separated,
and the water phase was extracted two times with methyl-tert-butyl ether.
The combinedorganic fractions were dried (MgSO4) and evaporated. The
resulting oil was dissolved in toluene (200 mL), p-toluenesulfonic acid (0.5
g) was added, and the mixture wasstirred at refluxfor 1 h. Aftercooling, the
reaction mixture was washed subsequently by a saturated aqueous solution
of NaHCO3 and brine and dried (MgSO4). Evaporation of solvent gave
20.4 g of the product (92% yield). Found, %: C, 91.87; H, 8.13. Calcd for
C21H22, %: C, 91.92; H, 8.08. 1H NMR (CDCl3, 20 °C): δ 2.0 (s, 3H), 2.1
(s, 3H), 2.0ꢀ2.2 (m, 2H), 2.3 (s, 3H), 2.4ꢀ2.7 (m, 2H), 2.8ꢀ3.1 (m, 3H),
6.5 (s, 1H), 6.9 (s, 1H), 7.0ꢀ7.3 (m, 3H). EIMS: m/z (%) 274 (M+, 100),
258 (43), 231 (29), 215 (25), 189 (8), 169 (9), 152 (8).
[4-(4-tert-Butylphenyl)-2-isopropyl-1H-inden-1-yl](dimethyl)(2-methyl-
4-phenyl-1,5,6,7-tetrahydro-s-indacen-1-yl)silane (15). n-BuLi (2.5 M)
in n-hexane (18.7 mL, 45 mmol) was added at ꢀ70 °C to a solution of 9
(10.0 g, 40.6 mmol) in Et2O (400 mL). The solution was slowly warmed
to room temperature and stirred for 3 h. The mixture was cooled to
ꢀ70 °C, and CuCN (135 mg, 1.5 mmol) and [4-(4-tert-butylphenyl)-2-
isopropyl-1H-inden-1-yl](chloro)dimethylsilane (14 g, 42.8 mmol) were
added. The mixture was warmed to room temperature and stirred for 5 h.
The resulting back slurry was passed through silica and evaporated to give
23.6 g of crude product, which was purified by column chromatography
(1200 g of silica gel, heptane/CH2Cl2, 5:l). Yield: 17.8 g (74%). Found,
%: C, 87.38; H, 8.33. Calcd for C46H52Si, %: C, 87.28; H, 8.28. 1H NMR
(CDCl3, 20 °C): δ ꢀ0.23, ꢀ0.16 (s, 6H), 1.10 (m, 3H), 1.25 (m, 3H),
1.39, 1.40 (s, 9H), 2.05 (m, 2H), 2.21 (s, 3H), 2.71(sept, 1H), 2.86ꢀ2.96
(m, 4H), 3.65, 3.69, 3.90, 3.97 (s, 2H), 6.49, 6.53 (s, 1H), 6.81, 6.83
(s, 1H), 7.17ꢀ7.51 (m, 13H). MS (direct): M+ = 592 (C43H48Si).
μ-Dimethylsilylene[η5-4-(4-tert-butylphenyl)-2-isopropyl-
1H-inden-1-yl](η5-2-methyl-4-phenyl-1,5,6,7-tetrahydro-s-in-
dacen-1-yl)dichlorozirconium(IV) (19). BuLi (2.5 M) in hexanes
(14 mL, 35 mmol) was added at ꢀ40 °C to a solution of 15 (10.4 g, 17.5
mmol) in 150 mL of diethyl ether. After the addition was complete, the
mixture was allowed to warm to room temperature and stirred for 3 h.
Solvents were removed under reduced pressure, pentane (200 mL) was
added, the mixture was cooled to ꢀ60 °C, and ZrCl4 (4.1 g, 17.5 mmol)
was added with stirring. After 1 h of stirring at ꢀ60 °C, Et2O (5 mL) was
added, and the mixture was gradually warmed to room temperature and
stirred overnight. The orange precipitate was then separated off on a G3
frit and washed with 50 mL of n-pentane. The orange residue on the frit
was dried under vacuum to give 11 g of crude complex (pseudo-rac/
pseudo-meso = 1:1, yield: 80%). This mixture was then refluxed in 150 mL
of DME within 16 h. The resulting solution was separated by decantation
and evaporated, and the residue was recrystallized from toluene/hexane,
giving 3.8 g of pure pseudo-rac-form. Yield: 29% (orange crystalline
powder). Found, %: C, 69.42; H, 6.38. Calcd for C46H50Cl2SiZr, %: C,
69.66; H, 6.35. 1H NMR (CDCl3, 20 °C): δ 1.07 (d, 3H), 1.10 (d, 3H),
1.32 (s, 6H), 1.37 (s, 9H), 2.00 (m, 2H), 2.20 (s, 3H), 2.82, 2.96 (m, 4H),
3.35 (sept., 1H), 6.65 (s, 1H), 7.01 (s, 1H), 7.06 (dd, 1H), 7.31 (t, 1H),
7.35 (d, 1H), 7.38 (s, 1H), 7.41 (t, 2H), 7.46 (d, 2H), 7.54 (broad, 2H),
7.62 (d, 1H), 7.64 (d, 2H). MS (direct): M+ = 750 (C43H46C12SiZr).
Preparation of the Catalysts. A 0.206 mmol sample of corre-
sponding zirconocene dichloride was added at room temperature to 43.3
mmol of MAO (30% toluene solution). The resulting solution was
allowed to stand overnight at room temperature and was subsequently
diluted with 10.9 mL of toluene. The diluted solution was carefully
added to 10 g of silica (Sylopol 948 (Grace-Davison), calcined at
600 °C). After 10 min, the catalyst suspension was evaporated and
dried in vacuo.
4,8-Dibromo-2-methyl-3,5,6,7-tetrahydro-s-indacen-1(2H)-one (12).
A suspensionofAlCl3 (73.2g, 542mmol) inCHCl3 (290 mL) wastreated
by a solution of 4 (45 g, 240 mmol) in CHCl3 (150 mL) at 0 °C under
vigorous stirring. After 1 h, the mixture was treated dropwisely with Br2
(24 mL, 480 mmol) in CHCl3 (50 mL) within 10 min at 0 °C, the cooling
bath was removed, and the solution was stirred overnight. The reaction
mixture was poured into ice water and extracted with CH2Cl2. The
combined organic phase was washed with aqueous NaHCO3 and water,
dried over MgSO4, and evaporated to dryness under vacuum to give 93 g
of a dark oil, which was gradually crystallized. This crude product was
suspended in 100 mL of n-heptane, stirred for 1 h at room temperature,
and filtered. A brown solid was obtained (52 g), and it was determined by
GC-MS to contain almost 100% of the target compound (yield: 63%).
The filtrate was concentrated, and the same procedure was repeated to get
10 g of the solid (total yield 62 g, 75%). Found, %: C, 45.48; H, 3.56; O,
1
4.70. Calcd for C13H12Br2O, %: C, 45.38; H, 3.52; O, 4.65. H NMR
(CDCl3, 20 °C): δ 1.31 (d, 3H), 2.16 (pent., 2H), 2.53 (dd, 1H), 2.75 (m,
1H), 3.07 (m, 4H), 3.22 (dd, 1H). 13C NMR (CDCl3, 20 °C): δ 16.5,
23.3, 34.7, 34.9, 35.8, 43.3, 115.5, 118.1, 133.9, 147.1, 152.7, 154.6, 205.5.
2-Methyl-4,8-phenyl-3,5,6,7-tetrahydro-s-indacen-1(2H)-one (13).
Obtained by the method used for 7. Yield: 97%. Found, %: C, 88.73;
H, 6.58; O, 4.69. Calcd for C25H22O, %: C, 88.72; H, 6.55; O, 4.73. 1H
NMR (CDCl3, 20 °C): δ 1.22 (d, 3H), 2.02 (pent., 2H), 2.53 (dd, 1H),
2.64 (m, 1H), 2.86 (m, 4H), 3.18 (dd, 1H), 7.34ꢀ7.50 (m, 10H). 13C
NMR (CDCl3, 20 °C): δ 16.4, 25.8, 32.0, 33.1, 33.8, 43.1, 127.3, 127.5,
127.6, 127.8, 127.9, 128.4, 128.6, 128.9, 129.0, 129.1, 132.0, 135.5, 136.0,
137.3, 138.3, 143.8, 150.2, 151.6.
6-Methyl-4,8-diphenyl-1,2,3,5-tetrahydro-s-indacene (14). Ob-
tained by the method used for 9. Yield: 94%. Found, %: C, 93.18; H,
6.82. Calcd for C25H22, %: C, 93.12; H, 6.88. 1H NMR (CDCl3,
20 °C): δ 2.00 (t, 2H), 2.04 (s, 3H), 2.84 (t, 2H), 2.90 (t, 2H), 3.24 (s,
2H), 6.44 (s, 1H), 7.35 (m, 2H), 2.44 (m, 8H). 13C NMR (CDCl3,
20 °C): δ 145.7, 143.0, 141.1, 140.6, 140.3, 139.9, 138.5, 133.5, 129.7,
129.5, 128.9, 128.2, 128.1, 126.8, 126.6, 126.3, 42.5, 32.8, 32.5, 31.9,
31.5, 26.1, 16.8.
Polymerizations. Propylene homopolymerizations with sup-
ported catalysts were carried out in a 10 L reactor charged with 3.5 kg
of liquid propene. The reactor was made inert by means of nitrogen
before being charged. Eight milliliters of a 20% strength by weight
solution of triethylaluminum in Exxsol (from Witco) was introduced
into the reactor, and the mixture was stirred at 30 °C for 15 min. If
hydrogen was added, its concentration was set to 0.5 standard liters per
liter of liquid propylene. A suspension of the respective catalyst in 20 mL
of Exxsol was introduced into the reactor. The reactor temperature was
increased to 65 °C and maintained at this temperature for 60 min.
Copolymerizations were carried out in a 10 L reactor charged with 3.5 kg
of liquid propylene. A 20% by weight solution of triethylaluminum in
Exxsol (from Witco) was introduced into the reactor, and the mixture
was stirred at 30 °C for 15 min. A suspension of the respective catalyst in
20 mL of Exxsol was introduced into the reactor. Ethylene was
introduced into the reactor (total of 160 g). The reactor temperature
was increased to 65 °C and maintained at this temperature for 60 min.
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The pressure in the reactor was maintained at 32 bar by continuous
addition of ethylene using a mass flow meter on closed loop control
(about 47 g of further ethylene introduced). The polymerizations were
stopped by venting the reactor. The polymers were dried overnight under
reduced pressure before being analyzed. Propylene homopolymeriza-
tions with homogeneous catalysts were conducted in a one-liter stainless-
steel B€uchi reactor equipped with an oil-circulating temperature control
bath. The reactor was swept with dry nitrogen at 110 °C for 1 h prior to
polymerization. At 25 °C 2ꢀ4 mL of a 1.0 M toluene solution of
triisobutylaluminum was added followed by 250 g of liquid propylene.
Stirring was initiated, and the reactor was heated to the polymerization
temperatures. Hydrogen was added (if required) at this stage. A toluene
solution of the zirconocene was reacted with a toluene solution of MAO
for 10 min, and polymerization was initiated by charging the catalyst
solution to the reactor with 50 g of liquid propylene under pressure. The
polymerization was stopped by venting and cooling the reactor.
Polymer Analysis. Determination of the Melting Point. The
melting point, Tm, was determined by means of a DSC measurement
in accordance with IS0 Standard 3146 in a first heating phase at a heating
rate of 20 °C per minute to 200 °C, a dynamic crystallization at a cooling
rate of 20 °C per minute down to 25 °C, and a second heating phase at a
heating rate of 20 °C per minute back to 200 °C. The melting point was
then the temperature at which the curve of enthalpy versus temperature
measured in the second heating phase displayed a maximum.
Gel Permeation Chromatography. Gel permeation chromatography
(GPC) was carried out at 145 °C in 1,2,4-trichlorobenzene using a
Waters 150C GPC apparatus. The evaluation of the data was carried out
using the software Win-GPC from HS-Entwicklungsgesellschaft fur
wissenschaftliche Hard- and Software mbH, Ober-Hilbersheim. The
columns were calibrated by means of polystyrene standards having
molar masses ranging from 100 to 107 g/mol. The mass average molar
mass (Mw) and number average molar mass (Mn) of the polymers were
determined. The Q value is the ratio of mass average molar mass (Mw) to
number average molar mass (Mn).
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental details for pre-
b
paration of similar bridged ligands and zirconocenes, crystal data
and processing parameters for complex 20, and CIF file giving
X-ray crystal structural data. This material is available free of
charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: inif@org.chem.msu.ru; Yoshikuni_Okumura@sdk.co.jp;
Michael.Elder@grace.com.
’ ACKNOWLEDGMENT
We thank LyondellBasell for financial support and permission
for publication of this work.
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13
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42.14 ppm, H2 is the peak at 30.82 ppm, and S[CH2] is the sum of all
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